Watermarking digital images to increase bit depth

摘要

Watermark data is converted to watermark coefficients, which may be embedded in an image by converting the image to a frequency domain, embedding the watermark in image coefficients corresponding to medium-frequency components, and converting the modified coefficients to the spatial domain. The watermark data is extracted from the modified image by converting the modified image to a frequency domain, extracting the watermark coefficients from the image coefficients, and determining the watermark data from the watermark coefficients. The watermark data may be truncated image data bits such as truncated least significant data bits. After extraction from the watermark, the truncated image data bits may be combined with data bits representing the original image to increase the bit depth of the image. Watermark data may include audio data portions corresponding to a video frame, reference frames temporally proximate to a video frame, high-frequency content, sensor calibration information, or other image data.

主权项

1. A computer-implemented method for compressing an image, the method comprising:
accessing an image comprising an array of pixels, each pixel comprising image data represented by a plurality of image data bits; truncating, for each pixel, a subset of least significant image data bits to produce an array of truncated pixels, each truncated subset of least significant image data bits collectively comprising a set of truncated image data bits; generating, by a processor, a watermark comprising a set of watermark coefficients representative of the set of truncated image data bits; generating a transformed image by converting the array of truncated pixels into a set of image coefficients in a frequency domain; embedding the watermark in the transformed image by modifying a subset of the image coefficients with the set of watermark coefficients to form a modified set of coefficients; generating a modified image by converting the modified set of coefficients into a spatial domain, the modified image representative of both the array of truncated pixels and the generated watermark; compressing the modified image to produce a compressed image; and storing the compressed image.